Phosphorothiolic acid ester compositions and methods of destroying insects



United StatcsPatent Ofiice PHOSPHOROTHIOLIC ACID ESTER COMPOSI- gggcslgaND METHODS OF DESTROYING- William R. Boon and Eric C. Edgar,Bracknell, Ranajit Ghosh and Norman Greenhalgh, Manchester, Hans S.Hopf, Bracknell, and BettyFlorence Burnand, Richmond, England, assignorsto Imperial Chemical Industries Limited, London, England, a corporationof Great Britain No Drawing. Application January 10, 1955 Serial No.481,032

Claims priority, application Great Britain December 22, 1954 9 Claims.(Cl. 167-22) This invention relates to new pesticidal compositionscontaining a phosphorus ester, as more particularly defined below and acarrier and if desired an auxiliary agent and/ or a plant nutrient.

The new compositions are useful against pests of the order Acarina,particularly the tetranychids or plantfeedlng mites, and also againstscale insects, e. g. Aonidiella aurantii mask, i. e. the Californian redscale. They are also toxic to some other plant pests, including aphids,e. g. Macrosiphum pisi, Aphis gossypii and Rhopolosiphium prunifoliae,and caterpillars e. g. Plutella maculipennis Curtis. Despite the hightoxicity of these compositions to such insects, they nevertheless showremarkable selective toxicity. They are only slightly toxic to someinsects, including Tribolium castaneum Dysdercus fasciatus, Micraspissexdecimpunctata and Locusta migratoria.

They may be in form suitable for direct application or in concentratedform suitable for application after dilution.

The said esters are phosphorothiolic acid esters of the general formula:

in which R and R stand for like or unlike alkyl radicals, L stands for asaturated straight or branched chain aliphatic hydrocarbon radical orfor such a radical in which the. carbon atoms are interrupted by anoxygen or sulfur atom or by a nitrogen atom carrying an alkylsubstituent, and X stands for a secondary aliphatic or heterocyclicamine attached to L through the amino nritogen atom or for a. salt ofsuch aliphatic or heterocyclic amine. Preferred esters are those whichnowhere contain a hydrocarbon radical with more than 4 carbon atoms. Theesters in which X stands for a secondary aliphatic or heterocyclic aminemay be made by the methods of copending U. S. application Serial No.391,121, filed November 9, 1953, and may be converted to salts in theordinary ways.

Although, as will be. shown, more fully below the simplest compositionsof the invention consist only of very dilute aqueoussolutions ofsuitable esters or their salts and we. anticipate that such solutions'orslight modifications of them. will find wide. application, neverthelesswe include in our invention, as indicated above, compositions whichcontain carriers other than water, compositions which contain auxiliaryagents and compositions which contain plant nutrients as wellascompositions which contain two or'more. of those ingredients in additionto the ester or esters. Carriers, auxiliary agents and plant nutrientsdo not comprise completely independent categories as sub stances can beused which act in two of these categories.

The carriers may be liquids or solids. A s liquids there maybe usedwater, as already mentioned, and nonphytocidal organic solvents. Theseliquids may beused 2,841,517 Patented. July 1, l 958 for both. forcompositions for direct application and for compositions in concentratedform suitable for use after dilution. Solid carriers include inertpulverulent diluents, e. g. talc, kieselguhr, bentonite and othercolloidal clays and powdered chalk. These carriers are used almost entirely for making pulverulent preparations for direct ap-- plication.For concentrated solid preparations there may be used other solidcarriers and more particularly watersoluble organic and inorganiccompounds; with these the toxic ingredient may be incorporated to give ashaped tablet or block or a non-hygroscopic free-flowing granularpreparation. Solids which have auxiliary or plant-nutrient propertiescan, in suitable cases, be used as carriers.

As auxiliary agents we mean substances other than carriers which assistin the preparation and. handling of the compositions or in theirapplication or which increase their effectiveness. Such auxiliary agentscomprise a miscellany of substances. Thus in making pulverulentcompositions, dust-binding agents such as spindle oil, glycerol and woolfat may be used. Wetting, spreading and dispersing agents such as sodiumdinaphthylmethane disulphonate and sodium lauryl sulphate and substancesadapted to promote adhesion or so-called sticking agents} such as glueand resin, may be used especially in liquid preparations. Plantnutrients, i. e. nutrients which are applied directly to the leaves orother above-ground portions of the plant as distinct from fertiliserswhich are applied indirectly to the plant through the ground (and whichare coming into increasing use) include such substances as urea andmagnesium sulphate.

Plant nutrients can, we have found, be in corporated into thecompositions of this invention and the resulting products can be appliedto plants and in this way results which would otherwise need twoapplications to the plants can be obtained by means of a singleapplication. Moreover certain plant nutrients can in some preparationsplay the part of carrier. Thus solid preparations may be made consistingof urea and an, ester, which can be dissolved in water to yieldsolutions which can be applied as combined nutritive-pesticidal washesand sprays.

In giving examples of specific carriers, auxiliary agents and plantnutrients and specific types of these as well as specific modes ofincorporation, we do this by way of illustration only and not by way ofconfining the invention to any or all of these.

For most purposes aqueous formulations are not only Consequently thedevising of formulations presents little or no difficulty in the.present invention.

The invention is of special interest in the control of Metatctranychusulmi and Tetranychus telarius, two

species of Tetranychidae commonly known in England as the fruit tree andglasshouse red spider mites respectively.

During recent years these and other red spider mites have become anincreasingly serious economic pest in horticulture and agriculture, on awide range of crops such as apples, citrus and COttOl'l. It is commonlybelieved that this is partly due to certain secondary eitects of theparticular pesticides which have been used. One

of these, di-p-chlorophenyltrichloroethane, although slightly toxic tored, spider mites, is much more toxic to their main predators whichunder normal conditions often exert a high degree of control on the redspider mites. Another one, namely diethyl p-nitrophenyl thio phosphate.(parathion), is like certain other organophosphorus compounds, highlytoxic to red spider mites and'has been widely used to treat cropsinfected with these pests. It is however not toxic to the eggs of thered spider mites nor does its toxic effect persist suffi cie'ntlylong'afte'r application to kill the larvae on hatching from theeggs,,and as a result it is' a frequent experience for a secondinfestation of the crop to develop which is much worse than the first.

- The esters ofthe above general formula have the prop-- erty that whilethey are highly toxic to red spider mites they are also sufiicientlypersistent for the larvae to be killed as they hatch from the eggs.

The efficacy of the esters maybe illustrated by tests which were carriedout on the use of O:O-diethyl S 3- diethylaminoethyl phosphorothiolatein the control of the glasshouse red spider, Tetranychus telarz'as onFrench bean plant (Phaseolus valgaris). On these it was examined as afoliage spray for contact and persistence activities'and in addition thesystemic and leaf-penetrating properties were tested.

The results showed that it was more active than any other acaricideknown to us. As a contact spray against adult redspiders it gave a 96%kill when used in the form of an aqueous spray containing only 0.0003%by weight of the ester. At a concentration of 0.0025 the solution whenpainted on the upper surface of the leaf killed 93% of the adult redspiders on the under surface. Diethyl p-nitrophenyl thiophosphate, awell known insecticide and acaricide hitherto considered active inpenetrating leaf tissues, isiinactive by comparison. This concentrationof 0.0025 will also give a complete kill of adult red spiders on leaveswhich are artificially infected 7 days after spraying.

As regards its systemic action, when the soil in which French beanplants were growing was watered with a solution of the ester (withoutwetting the plant) red spider mites on the leaves were killed.

The phytotoxicity of the compound is low. At 100 times the concentrationwhich gave complete kills of red spider no damage was caused either toFrench. bean or to tomato leaves (Lycopersicum esculentem).

The compound was also found active as a contact spray against aphids ata concentration of 0.002%.

As red spiders and aphids may occur together both may be destroyed bythe same preparation.

Field trials were carried out with O:O-diethyl S-fl-diethylaminoethylphosphorothiolate hydrogen oxalate,

against the fruit tree red spider mite, Metatetranychus almi, on appletrees. The results were outstandingly good. Almost complete control wasobtained throughout the season by one application of a 0.002% by weightaqueous solution in early June (in England). The treated trees wereimmune to a very severe infestation which developed on neighbouringuntreated trees in August and the laying of winter eggs was muchreduced. Also large bush apple trees severely infested and carrying apopulation of over 200 mites and eggs per leaf, were sprayed once with a0.004% or 0.002% by weight aqueous solutions in August. Four weeks laterno living mites could be found on these trees and no winter eggs weresubsequently deposited.

An infestation of Bryobia praetiosa Koch on a Morello cherry tree wascontrolled by spraying the tree once with the hydrogen oxalate ofO:O-diethyl S-B-diethylaminoethyl phosphorothiolate in the form of a0.002% by weight aqueous solution. Californian red scale, Aonidiellaaurantii Mask, was controlled completely in laboratory tests by sprayscontaining 0.05% of O:O'-diethyl S-p-diethylaminoethyl phosphorothiolatein aqueous solution. It was also found that when O:O'-diethyl S-B-diethylaminoethyl phosphorothiolate is applied to the roots of pot growncabbage plants, the larvae of Plutella maculipenriis Curtis feeding onthe leaves of the plants were killed.

The preparations are also efficacious against Aphis gossypii on cottonplants and red spider on tea plants.

The following examples in which parts are by weight illustrate but donot limit the invention.

Example 1 One part of O:O'-diethyl S-B-diethylaminoethylphosphorothiolate is dissolved in 2,000 parts of water.

This spray gave 100% kill of Aonidiella aurantii Mask (Californian redscale) in the laboratory.

Similarly, 1 part of O-ethyl O-methyl S-[3-diethylaminoethylphosphorothiolate is dissolved in 50,000 parts of water.

This spray gave a high kill of Tetranychus telarius on tomato plants.

Example 2 A mixture of 81 parts of O:O-diethyl S-fl-diethylaminoethylphosphorothiolate and 140 parts of diethyl ether is added to a solutionof 51 parts of p-toluenesulphonic acid in 1050 parts of ether. Theprecipitated ptoluenesulphonate salt of the base is collected byfiltration I and may be crystallised, if desired, from a mixture ofacetone and diethyl ether. It melts at 105 C. This salt is readilysoluble in water. As a 0.002% solution it is suitable as an acaricidalspray.

Example 3 O:O'-diethyl S-B-diethylaminoethyl dihydrogen citrate, M. P.94-95 C. is obtained from 108 parts of the base and 84 parts of citricacid following the procedure given under Example 3. A similarpreparation is obtainable by dissolving it in water.

Example 5 5 66 parts of O:O'-diethyl S-l-diethylamino-prop-2-ylphosphorothiolate are treated with a solution of 240 parts of oxalicacid dihydrate in 1640 parts of acetone and the mixture kept untilprecipitation of the salt is substantially complete (about 1 /2 hours).The solvent is then removed under reduced pressure and the residual oilysolid dried on a porous plate. If a pure product is desired, the crudesolid may be crystallised from a mixture of acetone and ether to givepure O:O'-diethyl S-l-diethylaminoprop- 2-yl phosphorothiolate hydrogenoxalate, M. P.

' 88.5-89.5 C. The salt is readily soluble in water to make a spraysuitable for aplication to foliage.

V Example 6 562 parts of O:O'-diethyl S-B-piperidinoethyl phos-' Yphorothiolate are dissolved in 410 parts of acetone and added to asolution of 252 parts of oxalic acid dihydrate in 1640 parts of acetone.When the precipitation of the salt'is substantially complete, the solidis collected by filtration. It may, if desired, be crystallised from amixture of ethanol and acetone to give pure O:O'-diethylS-fl-piperidinoethyl phosphorothiolate hydrogen oxalate, M. P. 124125'C. This salt is readily soluble in water to give a solution suitable foruse as an agricultural spray.

Example 7 566 parts of O:O'-diethyl S-B-morpholinoethyl phosphorothiolateare dissolved in 1400 parts of ether and added to asolution of 344' parts of p-toluene-sulphonic acid in 21,300 parts of 5:1.161". The salt which separates is collected by filtration and may, ifdesired, be crystallised from a mixtureof acetone and ether to give pure0:0- diethyl S-,B-morpholinoethyl phosphorothiolate p-toluenesulphonate,M. P. 122.5-1235" C. The salt is readily soluble in water to give asolution suitable for use as an agricultural spray.

Example 8 One part of O:O'-diethyl S-p-diethylaminoethylphosphorothiolate dihydrogen citrate and 640 parts of urea areintimately mixed.

1 part of this mixture is dissolved in 50 parts of water to give acombined acaricidal and nutrient spray.

Alternatively the mixture can be compressed into granules, tablets orbriquettes in order to make it more convenient for handling, packaging,storing and measuring.

Example, 10

20 parts of O:O-diethyl S-fi-diethylaminoethyl phosphorothiolate,

19,000 parts of citric acid and 28,000 parts of disodium phosphate aredissolved in 1,000,000 parts water. The excess of citric acid and thephosphate are added as bufiers.

Example 11 1 part of O:O'-diethyl S-,8-diethylaminoethylphosphorothiolate is dissolved in 1,000 parts of diacetone alcohol, (CHC(OH).CH .COCH to form a nonphytocidal plant spray.

Example 12 12 parts of O:O'-diethyl S-B-diethylaminoethylphosphorothiolate dihydrogen citrate is intimately mixed with 10,000parts of kieselguhr, and 90 parts of spindle oil to yield a non-dustingpulverulent composition.

Example 13 1 part of O:O'-diethyl S-B-piperidinoethyl phosphorothiolateor its oxalate, and 25 parts of sodium dinaphthylmethane disulphonateare dissolved in 25,000 parts of water. The resulting solution issuitable for use as a spray on plants which are difficult to wet.

Example 14 155 parts of O:O-diethy1 S-fi-diethylaminoethylphosphorothiolate are dissolved in 3,550 parts of dry ether and thesolution cooled in ice and saturated with dry hydrogen chloride. Thesolvent and excess hydrogen chloride are then removed under reducedpressure below 30 C. and the residue of O:O'-diethylS-fi-diethylarninoethyl phospho'rothiolate hydrochloride is isolated.This salt is readily soluble in water to form an agricultural spray.

What we claim is:

1. A pesticidal composition comprising an inert pesticide carrier and,as the active pesticidal ingredient, a ph'osphorothiolic acid ester ofthe general formula in which R and R stand for lower alkyl radicals, Lstands for a member of the group consisting of divalent saturatedaliphatic hydrocarbon radicals of up to four carbon atoms and divalentsaturated aliphatic hydrocarbon radicals of up to four carbon atoms inwhich the carbon atoms are interrupted by Z, Z being an atom selectedfrom the group consisting of oxygen, sulphur, and nitrogen carrying alower alkyl substituent, and X stands for a member of the groupconsisting of secondary aliphatic amines, piperidine and morpholineattached to L through the amino nitrogen atom and salts thereof.

2. A pesticidal composition according to claim 1 wherein said ester isfree from any hydrocarbon radical containing more than 4 carbon atoms.

3. A pesticidal composition according to claim 1 wherein said inertcarrier is a liquid.

4. A pesticidal composition according to claim 3 wherein said liquidcarrier is a non-phytocidal organic solvent for the ester.

5. A pesticidal composition according to claim 1 wherein said inertcarrier is water.

6. A pesticidal composition according to claim 1 wherein said inertcarrier is a solid.

7. A pesticidal composition according to claim 6 wherein said carrier isan inert pulverulent diluent selected from the group consisting of talc,kieselguhr, bentonite and powdered chalk.

8. A pesticidal composition according to claim 1 wherein said ester isselected from the group consisting of O:O'-diethyl,S-fi-diethylaminoethyl phosphorothiolate, its p-toluene sulphonate, itshydrogen oxalate, its hydrochloride and its dihydrogen citrate,O:O'-diethyl S-1- diethylaminoprop-Z-yl phosphorothiolate hydrogenoxalate, O:0-diethyl S-fi-piperidinoethyl phosphorothiolate hydrogenoxalate, O:O'-diethyl S-B-morpholinoethyl phosphorothiolatep-toluenesulphonate and O:O-diethyl S-fldi-n-propylaminoethylphosphorothiolate hydrogen oxalate.

9. The method of killing insects which comprises exposing the insects toa toxic quantity of a pesticidal composition according to claim 1.

Manufacture of Compressed Tablets, Silver, F. I. Stokes, 1944, p. 1.

1. A PESTICIDAL COMPOSITION COMPRISING AN INERT PESTICIDE CARRIER AND,AS THE ACTIVE PESTICIDAL INGREDIENT, A PHOSPHOROTHIOLIC ACID ESTER OFTHE GENERAL FORMULA